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1、22.3实际问题与一元二次方程(一)一、教学目标1.会利用一元二次方程解决传播问题.2.培养分析问题解决问题的能力,发展应用意识.二、教学重点和难点1.重点:利用一元二次方程解决传播问题.2.难点:根据传播问题列方程.三、教学过程(一)基本训练,巩固旧知1.填空:(1)有一人得了流感,他把流感传染给了10个人,共有人得流感;第一轮传染后,所有得流感的人每人又把流感传染给了10个人,经过两轮传染后,共有人得流感.(2)有一人得了流感,他把流感传染给了x个人,共有人得流感;第一轮传染后,所有得流感的人每人又把流感传染给了x个人,经过两轮传染后,共有人得流感.((1)题答案为11,121
2、,(2)题答案为1+x,1+x+x(x+1),先让生自己做,然后师进行讲解)(二)创设情境,导入新课师:和一元一次方程一样,利用一元二次方程可以解决实际问题,上节课我们做了一个例题,本节课我们再来看一个例题.(三)尝试指导,讲授新课(师出示下面的例题)例有一人得了流感,经过两轮传染后,共有121人得了流感,每轮传染中平均每一个人传染了几个人?师:大家把这个题目好好默读几遍.(生默读)师:谁能不看黑板说出题目的意思?生:……(让几名同学说)师:这个题目怎么设?afineof100Yuan.7.5.3accidentpenalties(1)injuriesfatalitiesdirec
3、tlypunished1~2million.Directresponsibilityfortheaccidentandhavethecorrespondingresponsibilityofleadership,suchasconcerningadministrativesanctions,shouldbebroughttothecompanyortherelevantDepartment.(2)personalinjuryaccidentoccurred,thedirectpunishment0.5-10,000yuan,responsibleforthedirectrespon
4、sibilityfortheaccidentandtheresponsibilityofleadership,suchasconcerningadministrativesanctionsshouldbedealtwithbythepersonnelDepartmentofthecompany.(3)personalinjuryaccidentoccurs,thedirectpunishment500-1000,whoisdirectlyresponsiblefortheaccidentresponsibility,givenoticeofcriticismand50-100eco
5、nomicsanctionsagainstthem.(4)toconcealtheaccident,reportedwithoutunduedelayorfalse,toinformtheadministrativeleadershipofthecriticism,resultinginseriousconsequences,thepursuitofleadership,alongwith500-1000punishment.(5)significantnearmissshouldbeattemptedasthecaseofresponsiblefortheaccidentandc
6、onstructionteaminjuriesaccidentpenaltyprovisions,mutatismutandis.Eight,shouldperformintheconstructionstandardsandspecifications,serialnumbera1GB3323-2005steelfusionweldedbuttjoints,weldingengineering-Raylightingandqualityratingof2GB11345-89steelweldsmanualmethodsofultrasonicinspectionandtestin
7、gresultsforgrade3GB50236-2002industrialpipeweldingengineeringcodeforconstructionandacceptanceoffieldequipment4HGJ222-92technicalspecificationforweldingofaluminiumanditsalloys5lowtemperaturesteelweldingprocedure6SH3525-2004petrochemicalJ